Technological Accomplishments
in Rouen Revisited

The execution of Rouen Revisited entailed more than half a dozen novel technical achievements in the modeling and rendering of architectural scenes from photographs. The most basic of these comprised Paul Debevec's Ph.D. thesis work at the University of California at Berkeley:

  • A photogrammetric modeling method, which facilitates the recovery of the basic geometry of a photographed scene. This photogrammetric modeling approach is effective, convenient, and robust because it exploits the constraints that are characteristic of architectural scenes.

  • A model-based stereo algorithm, which recovers how the real scene deviates from the basic model. By making use of the model, this stereo technique robustly recovers accurate depth from widely-spaced image pairs. Consequently, our approach can model large architectural environments with far fewer photographs than current image-based modeling approaches.

  • View-dependent texture mapping, a method of compositing multiple views of a scene that better simulates geometric detail on basic models.

Other achievements were more specific to the Rouen Revisited installation itself. For example, Rouen Revisited is probably the first time that:

  • A computer model of a building as complicated as a Gothic cathedral was recovered solely from photographs. The model we recovered, in fact, was derived from only three photographs of the façade.

  • Historic photographs were re-rendered from novel points of view, including points of view registered with new photographs and renderings, making it easier to see the changes over time.

  • An impressionist painter's point of view was recovered from a model of the subject and compared to known historical data of where he painted from.

  • Time series were presented in a manner such that views from any position can be shown at any time of day.

  • Impressionist paintings were re-rendered from novel points of view using image-based rendering techniques.

  • In several cases, two paintings of the same subject from different points of view were blended by first re-rendering one painting from the point of view of the other.

Other technical achievements were:

  • The development of an interactive method for accessing a multi-dimensional space of images, achieved though redundant striping of the image space into compressed movies and on-the-fly image blending.

  • The expansion of the lens field of view for some photographs by the use of homographic image stitching techniques.

  • The use of image rectification techniques to correct for inconsistent camera rotations across several interleaved photographic time series.

  • The discovery of a century-old attempt at multi-view image compositing.

Further information about the modeling and rendering algorithms used in Rouen Revisited can be found in:

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